The present invention relates to a semiconductor device and a manufacturing method thereof, which can be used appropriately as, e.g., a semiconductor device including a trench-gate field effect transistor and a manufacturing method thereof.
A trench-gate field effect transistor has a structure in which, in a trench formed in a main surface of a semiconductor substrate, a gate electrode is embedded via a gate insulating film.
Japanese Unexamined Patent Publication No. 2005-191268 (Patent Document 1) describes a technique related to a trench-gate power MOSFET.